You already knew that your skin is the largest organ you have — and it's no secret that this most exposed part of our body comes into contact with bacteria and other microorganisms, both "friendly" and harmful, on a daily basis, either.
We'll bet that you didn't know what the outermost layer of your skin is actually made of, though!
As one research paper pointed out, "The stratum corneum, the outer layer of the epidermis, is the most exposed organ of the human body and is composed of molecules derived from our own skin cells, our microbiota, and the environment."
The personal care products we use, the food we eat, and even the clothes we wear can also affect the composition of this particular skin layer, the research team added. As fascinating as science is, delving too deep into some rabbit holes can easily make us feel disgusted with our bodies — right?
In recent years (*cough, cough*), we have all upped our personal hygiene routine. Warnings to wash our hands often and properly have been drilled into us. While we probably never thought twice about touching our faces before COVID-19 emerged, ignoring those little itches and resisting the temptation to pull a stray strand of hair out of our faces has now become second nature.
What parts of your skin are harboring the most bacteria, and potentially the most dangerous ones?
1. The Hands
In one study, a research team roped one man and one woman into the unusual "job" of not showering, washing, or bathing for three days. Samples were taken before and after the project was complete to discover how bacterial and other microbial populations develop on the human body (more precisely the skin) over time.
It will surprise nobody that the hands were indeed found to be the "dirtiest" in this in-depth study of two people. Our hands are, in a sense, much like our skin — they're our interface with the rest of the world, and the body part we use to touch literally everything we interact with.
For this reason, the hands both carried the widest variety of bacterial species, and the highest total number. Bacteria and other microorganisms were not the only "dodgy" things found on the hands, either. Even after handwashing, chemicals we interact with turn out to remain on the skin, where they can even become part of the molecular makeup of its outer layer.
2. The Scalp
This one is surprising. The scalp was found to harbor a large number of Corynebacteria. Most of these species are harmless and exist in symbiosis with animals including humans. Although others cause disease, that likely was not the case here. The most interesting thing about the scalp is that it was found to "absorb" a variety of chemicals from the environment, which remained present for a long time. This is despite the fact that cell turnover is higher in this region of the skin, and scientists expected the head to cleanse itself of these environmental invaders more easily.
3. The Soles of the Feet
The soles of both subjects' feet were also extraordinarily high in bacterial variety, making the feet one of the germiest spots on the body. This will in part be caused by the fact that the feet are generally rather sweaty. What was interesting, though, is that even dangerous Staph bacteria were found on both subjects' soles.
4. On the Nose
Everyone already knows that bacteria hide in large numbers within the nasal cavity. Research further shows that the outside of the nose may be home to a large concentration and variety of bacterial species that, again, include Staph. Once on the nose, it's only a short way to reach the nostrils and travel further down the respiratory tract. This could be a sign that we need to pay more attention to washing our noses.
5. Under the Breasts
In women, the area immediately under the breast is another haven for bacteria and other microorganisms. When the female study subject stopped washing as instructed, bacteria immediately began to accumulate in precisely that spot. The reason is, again, likely linked with sweating. The same, likely, is true for any moist skin fold that may be found on the body, especially in overweight people.
As a bonus, another study identified the belly button as an especially germy spot, likely because even though we diligently wash all other parts of the body, that one is often overlooked.
Surprising Lessons from a Novel Kind of Study
This small-scale but in-depth study does not offer universal answers. It does show what can happen when we don't practice personal hygiene. Bacteria were found literally all over the body, of course, as were environmental chemicals. The only place that many bacteria seemed to hate? An oily forehead! This spot is apparently hostile to a great many bacterial species, and most protected in the event that you stop washing your body.
The parts of the body that we'd typically consider to be "dirtiest", the genital region and the armpits, didn't stand out in terms of bacterial variety or even numbers, on the other hand. The female study subject also continued using deodorant. Since the man did not, we're assuming that she was asked not to but simply couldn't stand the body odor.
Personal hygiene is such an important part of our daily lives. In the modern world, few people who aren't participating in a cool study to map the presence of bacteria on the body would choose not to wash — so this scenario is definitely preventable.